WO2012004979A1

WO2012004979A1 - Rotational vibration gyro

Info

Publication number: WO2012004979A1
Application number: PCT/JP2011/003829
Authority: WO
Inventors: 哲郎杉田; 三朗伊藤; 大介平山; 山村　雄一
Original assignee: パイオニア株式会社; パイオニア・マイクロ・テクノロジー株式会社
Priority date: 2010-07-05
Filing date: 2011-07-05
Publication date: 2012-01-12
Also published as: JP4939671B2; WO2012004825A1; JPWO2012004825A1

Abstract

Provided is a rotational vibration gyro which achieves improvement in the degree of freedom of design regarding flexural and torsional characteristics of a support spring. Disclosed is a rotational vibration gyro (1) characterized by being provided with a movable weight (4) which is released above a substrate (2) and has a slit (8) passing the center of gravity and extending in the axial direction of a detection axis, a drive electrode (3) which rotationally vibrates the movable weight (4) around the Z axis that passes the center of gravity thereof, a detection electrode (9) which detects the displacement of the movable weight (4) that is swung around the detection axis by Coriolis force, an anchor (6) which is provided so as to project from the substrate (2) and inserted into the slit (8) concentrically with center of gravity and supports the movable weight (4), and two rows of support springs (7) which are hung between the anchor (6) and the movable weight (4), are parallel in the detection axis direction, and are disposed line-symmetrically with respect to the detection axis.

Description

Rotating vibration gyro

The present invention relates to a rotational vibration gyro that detects angular velocity in one axis.

Conventionally, an annular drive weight released on a silicon substrate and a disc-shaped detection weight arranged concentrically on the inside of the drive weight are provided, and the drive weight is rotated and oscillated around the Z axis passing through its center of gravity. Thus, there is known a rotary vibration type gyro that swings a detection weight by a Coriolis force generated when an angular velocity is applied about an axis orthogonal to the Z axis, and detects the angular velocity from a change in capacitance due to the swing. (See Patent Document 1).
In this gyro, a pair of detection springs are spanned on an axis (detection axis) that is the center of vibration caused by Coriolis force from a pair of anchors protruding from both sides of the detection weight to the substrate. The detection weight swings by the spring functioning as a hinge of the detection weight. On the other hand, drive springs that span between the drive weight and the detection weight and absorb the rotational vibration of the drive weight and transmit only the Coriolis force to the detection weight are arranged in four directions inclined by 45 ° with respect to the detection shaft. Has been.

Conventionally, a movable weight (vibration mass) released on the substrate and having an opening in the center, a drive electrode (comb structure) for rotating the movable weight around the Z axis passing through its center of gravity, and a detection axis (X A detection electrode for detecting the displacement of the movable weight that swings around the axis) by the Coriolis force, and an anchor that protrudes from the substrate and is inserted concentrically with the center of gravity and through the opening of the movable weight to support the movable weight A support spring that is spanned between the (support point), the anchor, and the movable weight, is parallel to the direction of the detection axis (X-axis), and is arranged in line symmetry about the detection axis. A rotational vibration type gyro is known (see Patent Document 2).
In this rotational vibration type gyro, when the movable weight is rotating and oscillating around the Z axis, when the angular velocity around the Y axis is received, the movable weight is minutely oscillated around the detection axis (X axis) by the generated Coriolis force. To do. At this time, the capacitance of the detection electrode changes periodically, and the angular velocity received from this change can be detected.

International Publication No. 2010-016094 Japanese National Patent Publication No. 11-513111

By the way, in this type of gyro, the drive weight, the detection weight, the drive spring, the detection spring, and the like are formed by being subjected to an etching process in multiple stages with respect to the silicon substrate. Actually, in this etching process, it is difficult to etch perpendicularly with respect to the surface of the substrate, and the cross-sections of the detection spring and the drive spring formed in an elongated shape may be formed in a parallelogram. is there. In such a case, in particular, in each drive spring, upper and lower component forces act in addition to left and right bending forces due to rotational vibration. The upper and lower component forces act in opposite directions in the two drive springs that are symmetric with respect to the center of gravity of the movable weight, so that a vibration different from the Coriolis force is generated in the detection weight. This vibration is generated around an axis perpendicular to the extending direction of the drive spring. In the gyro described above, this vibration is generated in two directions inclined by 45 ° with respect to the detection axis due to the arrangement of the drive spring, so that it interferes with the swing to be detected as noise and cannot accurately detect the angular velocity. There is a problem.

In addition, here, such a rotational vibration type gyro arbitrarily changes characteristics and resonance gain (detection sensitivity) with respect to disturbance by changing resonance frequencies around the Z axis and around the detection axis (X axis). be able to. For example, when the resonance frequency around the X axis (hereinafter referred to as “detection frequency”) is higher than the resonance frequency around the Z axis (hereinafter referred to as “drive frequency”), disturbances such as temperature changes and shocks are caused. A rotary vibration gyro having characteristics that are not easily affected can be configured.

In the rotational vibration type gyro described in Patent Document 2, the movable weight is supported by one support spring provided between both sides of the anchor. In order to change the characteristics of the support spring and change the characteristics of the rotational vibration gyroscope by changing each resonance frequency, it is conceivable to change the width and thickness of the support spring. However, the characteristic of the support spring cannot be changed greatly only by changing the design of one support spring, and it is difficult to arbitrarily set the drive frequency and the detection frequency.

An object of the present invention is to provide a rotational vibration gyro capable of accurately detecting an angular velocity. Another object of the present invention is to provide a rotary vibration type gyro that can improve the degree of freedom in design with respect to the bending and twisting characteristics of the support spring.

The rotational vibration type gyro of the present invention is a movable weight that is released on a substrate and has a slit opening that passes through the center of gravity and extends in the axial direction of the detection shaft, and a drive that rotationally vibrates the movable weight about the Z axis that passes through the center of gravity. An electrode, a detection electrode for detecting the displacement of a movable weight that swings around the detection axis by a Coriolis force, an anchor that protrudes from the substrate and is inserted concentrically with the center of gravity and through the slit opening to support the movable weight; And two rows of support springs that are spanned between the anchor and the movable weight, are parallel to the detection axis direction, and are arranged symmetrically about the detection axis.

In this case, it is preferable that the support spring is stretched from at least one of both sides of the anchor to at least one of both opening edge portions constituting both ends of the slit opening in the axial direction of the detection shaft.

According to these configurations, two rows of support springs are stretched between the anchor and the movable weight. For this reason, characteristics of the support spring (for example, spring constant, bending rigidity, torsional rigidity, etc.) are adjusted by adjusting the shape (cross-sectional shape, planar shape, etc.) of the support spring for each row and adjusting the distance between the rows. ) Can be changed arbitrarily. As a result, the design flexibility of the support spring is improved, and the drive frequency (around the Z axis) and the detection frequency (around the detection axis (X axis)) can be arbitrarily set. A gyro can be constructed.

In this case, the support spring is preferably formed in a folded shape in an “S” shape.

In this case, it is preferable that the folded portion folded in an “S” shape is formed wider than the other portions.

According to these configurations, not only the degree of freedom in setting each resonance frequency is improved with the improvement in the degree of freedom in design of the support spring, but also the vibration in the Z-axis direction (pitch) that becomes noise during angular velocity detection is suppressed. Can do. In particular, by forming the folded portion folded back in an “S” shape wider than the other portions, it is possible to more effectively suppress the swing in the Z-axis direction. The applicant of the present application makes the “S” shape of the support spring, so that “vertical displacement / rotational displacement around the Z axis (drive displacement)” in the non-resonant state is 1 / compared to the straight support spring. It is confirmed that it is suppressed to about 2 to 1/3.

In this case, it is preferable that the two rows of support springs are largely separated on the movable weight side and small on the anchor side.

Here, in order to increase the difference between the drive frequency and the detection frequency (drive frequency <detection frequency), the interval between the two rows of support springs must be increased. However, widening the distance between the support springs on the anchor side requires that the anchor itself be made large, which increases the size of the rotary vibration gyro.
Therefore, according to this configuration, the distance between the two rows of support springs is narrower on the anchor side, so that the anchor can be formed smaller. Thereby, size reduction of a rotational vibration type gyro can be achieved.

It is the top view (a) and sectional drawing (b) of the rotational vibration gyroscope which concern on 1st Embodiment. It is a top view of the rotational vibration type gyro which concerns on the 1st modification of 1st Embodiment. It is the graph which showed the relationship between the spring space | interval and each frequency in the rotational vibration gyroscope which concerns on the 1st modification of 1st Embodiment. It is a top view of the rotational vibration type gyro which concerns on the 2nd modification of 1st Embodiment. It is a top view of the rotational vibration type gyro according to a second embodiment. It is a top view of the rotational vibration type gyro which concerns on the modification of 2nd Embodiment. It is a top view of the rotational vibration type gyro according to a third embodiment. It is a top view of the rotational vibration type gyro which concerns on 4th Embodiment. It is a top view of the rotational vibration type gyro which concerns on the modification of 4th Embodiment. It is a top view of the rotational vibration type gyro according to a fifth embodiment. It is a top view of the rotational vibration gyroscope concerning 6th Embodiment. It is the graph which showed the relationship between the folding | turning part of each support spring and the Z-axis direction displacement amount per 1 micrometer of drive displacements in the rotational vibration gyroscope which concerns on 6th Embodiment. It is the graph and table | surface which showed the relationship between the spring space | interval and each frequency in the rotational vibration type gyro which concerns on 6th Embodiment.

Hereinafter, a rotational vibration gyro according to an embodiment of the present invention will be described with reference to the accompanying drawings. This rotational vibration type gyroscope is a uniaxial angular velocity sensor in a MEMS (micro-electro-mechanical system) sensor manufactured by microfabrication technology using silicon or the like as a material, and is driven by reciprocating reciprocal rotational vibration in a plane. And the thing of embodiment is packaged in about 1 mm square and is commercialized. Here, in the plan view, the description will be made assuming that the left-right direction is the “X-axis direction”, the up-down direction is the “Y-axis direction”, and the penetration (front-rear) direction is the “Z-axis direction”.

As shown in FIG. 1, the rotational vibration gyro 1 according to the first embodiment includes a plurality of sets (eight sets in the present embodiment) of drive electrodes 3 and a plurality of sets positioned on the outermost periphery on the substrate 2. In the X-axis direction between the anchor 6 and the movable weight 4, the flat circular movable weight 4 disposed inside the drive electrode 3, the anchor 6 disposed at the center of the movable weight 4, and the movable weight 4. A pair of extending support springs 7 and 7 and a pair of

detection electrodes

9 and 9 for detecting the displacement of the movable weight 4 are provided. The rotational vibration gyro 1 includes a sealing member 12 that seals the above-described constituent elements on a substrate 2.

In this case, the movable weight 4 and the support spring 7 constitute a movable part of the rotary vibration gyro 1 and are supported on the substrate 2 via the anchor 6. This movable part is formed by etching the substrate 2 made of silicon. Similarly, a fixed detection electrode 32 to be described later is supported on the substrate 2 and above the movable weight 4. The movable weight 4 (same as the support spring 7) is composed of a conductive member, and the movable drive electrode 22 and the movable detection electrode 31 described later are composed of a part of the movable weight 4.

The plurality of drive electrodes 3 are arranged at equal intervals in the circumferential direction outside the movable weight 4. Each drive electrode 3 includes a fixed drive electrode 21 integrally formed on the substrate 2 and a movable drive electrode 22 provided as a part of the movable weight 4 so as to extend radially outward from the outer peripheral end of the movable weight 4. And is composed of. The fixed drive electrode 21 and the movable drive electrode 22 are opposed to each other in the form of comb teeth, and by applying an AC voltage thereto, a movable weight is generated by an electrostatic force generated between the

electrodes

21 and 22. 4 rotates and vibrates around the Z-axis (around the center of gravity).

The movable weight 4 is formed in a flat plate shape centered on the Z axis. Needless to say, the movable weight 4 is formed vertically and symmetrically (in the Y-axis direction) with respect to the X-axis (detection axis) serving as the center of vibration due to the Coriolis force.

The anchor 6 is disposed so as to pass through a slit 8 having a rectangular shape in plan view formed at the center position of the movable weight 4, and is erected integrally on the substrate 2 so as to be slightly higher than the movable weight 4. . In this case, the anchor 6 is formed in a columnar shape, and the pair of support springs 7 and 7 extend linearly on the X axis from both side surfaces thereof. Each support spring 7 is stretched between the anchor 6 and the edges 11 and 11 (opening edge edges) of the slit 8 to support the movable weight 4 in a state of being lifted from the substrate 2.

Each support spring 7 is formed in a narrow cross-sectional rectangle, allows rotation of the movable weight 4 and functions as a hinge shaft of the movable weight 4 that vibrates due to Coriolis force. That is, the support spring 7 functions as a so-called torsion spring. As a result, the movable weight 4 receiving the Coriolis force vibrates like a seesaw around the pair of support springs 7 and 7 with one half and the other half in the Y-axis direction. That is, the movable weight 4 swings around the X axis (detection axis) by Coriolis force.

The pair of detection electrodes 9 includes a pair of

movable detection electrodes

31 and 31 formed of one half and the other half of the movable weight 4 made of a conductive material in the Y-axis direction, and a pair of movable detection. A pair of fixed detection electrodes (fixed detection electrode portions) 32, 32 facing the upper side with a capacitance gap 33 (which is larger than the amplitude of the movable weight 4) 33 being a minute gap with respect to the

electrodes

31, 31; It consists of When the movable weight 4 vibrates like a seesaw due to the Coriolis force, the capacitance between the movable detection electrode 31 and the fixed detection electrode 32 changes, and the angular velocity is detected based on this change. In the embodiment, when the movable weight 4 is in a state of rotational vibration and receives an angular velocity around the Y axis, the movable weight 4 slightly vibrates around the X axis due to the generated Coriolis force. Thereby, the electrostatic capacitance of a pair of

detection electrodes

9 and 9 changes, and the received angular velocity is detected.

Each fixed detection electrode 32 is formed in a plane shape that is substantially the same shape as the movable detection electrode 31 constituted by a half of the movable weight 4, and is substantially at the same position in the X-axis direction and the Y-axis direction with respect to the corresponding movable detection electrode 31. They are arranged in parallel. Each fixed detection electrode 32 is made of polysilicon or the like formed on the sacrificial layer, and is supported by a plurality of electrode support portions (not shown) spaced apart on the substrate 2. That is, the pair of fixed

detection electrodes

32 and 32 and the pair of electrode support portions are produced by removing the sacrificial layer by etching or the like. Each fixed detection electrode 32 may be formed on the sealing member 12.

The sealing member 12 is made of a so-called glass plate and is anodically bonded to the edge of the substrate 2. Inside the sealing member 12, an extraction wiring connected to the upper surface of the anchor 6 (movable detection electrode 31) and an extraction wiring connected to each fixed detection electrode 32 are formed (both not shown). In addition, you may comprise the sealing member 12 with a silicon substrate or a drive IC chip.

As described above, the pair of support springs 7 and 7 are formed by etching the substrate 2. However, in the actual etching process, it is difficult to etch perpendicularly with respect to the surface of the substrate 2. The cross section of the spring 7 may not be an ideal rectangle but a parallelogram. In this case, a vertical component force acts on the pair of support springs 7 and 7 in addition to the left and right bending forces due to the rotational vibration of the movable weight 4, and the vertical component forces are a pair of support springs at symmetrical positions. 7 and 7 work in the opposite direction. The vibration of the movable weight 4 generated by the upper and lower component forces is a vibration generated under the influence different from the Coriolis force, and becomes a noise of a vibration to be detected.

However, in the rotational vibration gyro 1 of the present invention, since the pair of support springs 7 and 7 extend in parallel to the X-axis direction (the axial direction of the detection shaft), the vibration of the movable weight 4 due to the vertical component force. Occurs around the Y axis. That is, the vibration of the movable weight 4 as noise is generated orthogonal to the vibration to be detected. Since the detection electrode 9 detects a change in capacitance due to vibration centered on the X axis, the vibration centered on the Y axis that becomes noise is canceled capacitively, and only the vibration of the detection target is detected. Is done. With such a configuration, the rotational vibration gyro 1 of the present invention can accurately detect the angular velocity.

Next, with reference to FIG. 2, a rotational vibration gyro 1 according to a first modification of the first embodiment will be described. In addition, the description similar to what concerns on 1st Embodiment mentioned above is abbreviate | omitted.

As shown in FIG. 2, the rotational vibration gyro 1 according to the first modification is provided with two pairs (two rows) so that a pair of support springs 7 and 7 extending in the X-axis direction are parallel to each other. ing. That is, the two rows of support springs 7 are parallel to the X-axis (detection axis) direction, and are arranged symmetrically about the X-axis. The pair of two-row support springs 7 and 7 extend linearly from both side surfaces of the anchor 6 formed in a prismatic shape, and span the edge portions 11 and 11 (opening edge portions) of the slit 8. Has been.

Here, the rotational vibration type gyro 1 can arbitrarily change characteristics and resonance gain (detection sensitivity) with respect to disturbance by changing resonance frequencies around the Z axis and around the X axis. For example, when the resonance frequency (detection frequency) around the X axis is higher than the resonance frequency (drive frequency) around the Z axis, the rotational vibration gyro 1 having characteristics that are not easily affected by disturbances such as temperature changes and impacts is provided. If it is configured and reversed (driving frequency> detection frequency), the rotational vibration gyro 1 with good detection sensitivity is configured.

Since the support springs 7 of the rotational vibration gyro 1 according to this modification are provided in two rows so as to be parallel to each other, the movable weight 4 can be stably supported on the substrate 2. Further, by adjusting the shape (cross-sectional shape, planar shape, etc.) of the support spring 7 for each row and adjusting the distance between the rows, the characteristics (for example, spring constant, bending rigidity and twist) of each support spring 7 are adjusted. Stiffness etc.) can be arbitrarily changed.

FIG. 3 is a graph showing the relationship between the spacing between the two rows of support springs 7 (spring spacing S) and each frequency. As shown in FIG. 3, when the interval between the two rows of support springs 7 (spring interval S) is increased, the value of the drive frequency is substantially constant, whereas the value of the detected frequency is less than the value of the drive frequency. In the range of That is, as the detection frequency changes, the difference from the drive frequency relatively changes. In this case, the spring interval S can be designed freely within a range where the relationship of “drive frequency> detection frequency” is satisfied. Thus, since the value of the detection frequency (around the X axis) can be arbitrarily set with respect to the drive frequency (around the Z axis), the rotational vibration gyro 1 having desired characteristics can be configured.

In addition, the black squares and triangles in the graph of FIG. 3 are the drive frequency and the detection frequency when the support spring 7 is in one row (one). Thus, by arranging the support springs 7 in two rows, the rotational vibration gyro 1 having a frequency characteristic different from the case where the support springs 7 are in one row (one) can be configured. Thereby, the design freedom of the rotational vibration type gyro 1 is improved.

Next, the rotational vibration gyro 1 according to the second modification of the first embodiment will be described with reference to FIG. In addition, the description similar to what concerns on 1st Embodiment mentioned above is abbreviate | omitted.

As shown in FIG. 4A, the rotational vibration gyroscope 1 according to the second modification includes a pair of semicircular

movable weights

41, 41 in which a disk-shaped movable weight 4 is divided into two on the X axis. It consists of In this case, the pair of semicircular

movable weights

41, 41 have

cutout portions

42, 42 at the center of the opposite sides, respectively, and the anchor 6 is located between the

cutout portions

42, 42 at the center of the movable weight 4. Is inserted. On the other hand, the two pairs of support springs 7 and 7 are arranged so as to be parallel to each other in the X-axis direction of the detection axis, from the both side surfaces of the anchor 6 to the edge portions 43 and 43 (notch ends) (Over the edge). In addition, the pair of semicircular

movable weights

41, 41 are coupled at positions outside the

cutout portions

42, 42, and the pair of movable

semicircular weights

41, 41 are kept constant with respect to each other. Weight connection springs 44, 44 are provided. Each movable weight coupling spring 44 couples a pair of semicircular

movable weights

41 and 41 via a pair of

spring support portions

45 and 45 disposed on opposite sides of the pair of semicircular

movable weights

41 and 41. . In addition, as shown in FIG.4 (b), you may comprise the anchor 6 by inserting into each

notch part

42 and 42, and comprising a pair of things arrange | positioned line-symmetrically centering on the detection axis.

According to this configuration, by dividing the movable weight 4, the detection weight 102 can move in the same direction with respect to the external force from the Z-axis direction, and by taking the difference between the vibrations of the two detection weights 102. The excess noise component can be canceled, the movable weight 4 can be prevented from being damaged, and the durability of the movable part can be improved. Further, the pair of connecting

springs

44 and 44 can be oscillated in the same phase with respect to the external force of the Z-axis rotation by the movable

weight connecting springs

44 and 44.

Subsequently, a rotational vibration gyro 1 according to another embodiment of the present invention will be described with reference to FIGS. In the following description, detailed description of the same configuration as in the first embodiment is omitted, and the same reference numerals are used. The following other embodiments can also be applied to the various modifications according to the first embodiment.

FIG. 5 shows a rotational vibration gyro 1 according to a second embodiment of the present invention. As shown in the figure, the rotational vibration gyro 1 according to the present embodiment has two slits 8 formed on the movable weight 4 so as to be symmetrical with respect to the X axis and the Y axis. Each of the anchors 6 is inserted through the. Each anchor 6 is disposed in each slit 8 on the X axis and at a position away from the center of the movable weight 4, and a support spring 7 is stretched from the inner surface of each anchor 6 to the edge 11 of the slit 8. ing. That is, the

anchors

6 and 6 and the support springs 7 and 7 disposed in each slit 8 are arranged symmetrically about the X axis and the Y axis.

As shown in FIG. 6A, each anchor 6 is disposed in a position near the center of the movable weight 4 in each slit 8, and the support spring 7 is connected to the edge of the slit 8 from the outer surface of the anchor 6. It may be configured to span over the section 11. Further, as shown in FIG. 6B, each anchor 6 is disposed in the center of the slit 8, and a pair of support springs 7 and 7 are provided for each anchor 6 from each side of the anchor 6 to each edge of the slit 8. 11 may be used.

FIG. 7 shows a rotational vibration gyro 1 according to a third embodiment of the present invention. As shown in the figure, the rotational vibration gyro 1 according to the present embodiment has three slits 8 formed on the movable weight 4 so as to be symmetrical about the X axis and the Y axis. Each of the anchors 6 is inserted through the. In the slit 8 formed in the center, the anchor 6 is disposed in the center of the slit 8, and a pair of support springs 7, 7 are spanned from both side surfaces of the anchor 6 to both

edges

11, 11 of the slit 8. ing. On the other hand, in the

slits

8 and 8 formed at positions away from the center, each anchor 6 is disposed on the X axis and at a position away from the center of the movable weight 4, and the slit 8 is formed from the inner surface of each anchor 6. The support springs 7 are stretched over the edge 11 of each. That is, the

anchors

6 and 6 and the support springs 7 and 7 disposed in each slit 8 are arranged symmetrically about the X axis and the Y axis. As described above, the present embodiment is configured by combining the first embodiment and the second embodiment.

FIG. 8 shows a rotational vibration gyro 1 according to a fourth embodiment of the present invention. As shown in the figure, the rotational vibration gyro 1 according to the present embodiment does not have the slit 8 in the movable weight 4 and has a pair of

anchors

6 and 6 outside the movable weight 4. The pair of

anchors

6, 6 are arranged on the X axis, and a pair of support springs 7, 7 are spanned from the inner surface of each anchor 6 to each outer

peripheral end

51, 51 of the movable weight 4. The pair of

anchors

6 and 6 and the pair of support springs 7 and 7 are arranged in line symmetry with respect to the X axis and the Y axis as a center.

In addition, as shown in FIG. 9, the anchor 6 provided outside the movable weight 4 may be formed in a frame shape so as to surround the movable weight 4. In this case, a pair of

spring coupling portions

52, 52 are formed on the inner surface of the anchor 6 on the X axis, and a pair of support springs 7 extends from the

spring coupling portions

52, 52 to the respective outer

peripheral end portions

51, 51 of the movable weight 4. , 7 are spanned. Although the anchor 6 has a rectangular frame shape in the drawing, it may have any shape as long as the shape surrounds the movable weight 4.

According to the rotational vibration gyro 1 described so far, the movable weight 4 has a function of a so-called drive weight 101 and a detection weight 102, and the support spring 7 has a function of a so-called drive spring and detection spring. Therefore, the structure of the movable part can be simplified and the manufacture of the device can be simplified.

FIG. 10 shows a rotational vibration gyro 1 according to a fifth embodiment of the present invention. The rotational vibration gyro 1 according to the present embodiment has a configuration in which the movable weight 4 in the above embodiment is separated into a drive weight 101 and a detection weight 102. The drive weight 101 is formed in an annular shape, and a large number of drive electrodes 3 are arranged at equal intervals around the drive weight 101. On the other hand, the detection weight 102 is formed in a disc shape and is disposed inside and concentrically with the drive weight 101. Further, a pair of

movable detection electrodes

31, 31 constituted by one half and the other half of the detection weight 102 in the X-axis direction, and a fixed disposed directly above the pair of

movable detection electrodes

31, 31. The detection electrode 9 is configured by the

detection electrodes

32 and 32.

A slit 8 is formed at the center position of the detection weight 102, and a pair of

notches

111, 111 are formed at both ends on the X axis. Further, an anchor 6 erected from the substrate 2 is inserted into the slit 8. In each notch 111, a connecting spring 114 is stretched from the inner edge 112 of the drive weight 101 to the edge 113 of the notch 111. Further, in the slit 8, a pair of support springs 7 and 7 (detection springs) are spanned between both side surfaces of the anchor 6 and each edge 11 of the slit 8.

The connection spring 114 absorbs the rotational vibration of the drive weight 101 by the drive electrode 3 and transmits Coriolis force to the detection weight 102. Further, the coupling spring 114 and the support spring 7 function as a hinge of the detection weight 102 that vibrates due to Coriolis force. In this case, the coupling spring 114 and the support spring 7 are disposed so as to extend in parallel with the X-axis direction.

Note that the detection weight 102 may be formed in an annular shape, and the drive weight 101 formed in a disk shape may be disposed inside the detection weight 102 and concentrically. In this case, it is preferable that the connection spring 114 that connects the detection weight 102 and the drive weight 101 extends so as to be parallel to the axial direction of the X axis.

According to the rotational vibration type gyro 1 of the present invention described so far, the support spring 7 (the coupling spring 114 and the support spring 7) functioning as a hinge of the movable weight 4 (detection weight 102) that vibrates about the X axis is provided. Since it extends in parallel with the axial direction of the X axis, which is the detection axis of the movable weight 4, it is possible to limit the vibration that becomes noise to a direction orthogonal to the vibration that is the detection target. Therefore, it is possible to accurately detect the vibration and accurately detect the angular velocity without causing the vibration as noise to interfere with the vibration to be detected.

FIG. 11 shows a rotational vibration gyro 1 according to a sixth embodiment of the present invention. As shown in FIG. 11, the rotational vibration gyro 1 of the present embodiment is similar to that according to the first modification of the first embodiment described above, with a pair of two rows of support springs 7 extending in the X-axis direction. 7. Each support spring 7 is folded in an “S” shape toward the outside near the center in the Y-axis direction. That is, the two rows of support springs are spaced farther apart on the movable weight 4 side than on the anchor 6 side. Each support spring 7 has a folded portion 13 folded in an “S” shape so as to be wider (thicker) than the other portions.

FIG. 12 is a graph showing the relationship between the folded portion 13 of each support spring 7 and the amount of displacement in the Z-axis direction per 1 μm of drive displacement. As shown in FIG. 12, as the width of the folded portion 13 of each support spring 7 is increased, the amount of displacement in the Z-axis direction that occurs during drive rotation ("longitudinal displacement / rotational displacement around the Z-axis (drive Displacement) ”) is decreasing. As a result, the degree of freedom in setting the detection frequency and the drive frequency is improved as the design flexibility of each support spring 7 is improved, and the Z-axis direction vibration (vertical displacement), which becomes noise during angular velocity detection, is suppressed. can do. Note that. The applicant of the present application confirms that the longitudinal displacement is suppressed to about ½ to ３ compared to the straight support spring 7 by making each support spring 7 into an “S” shape. is doing.

FIG. 13 is a graph and a table showing the relationship between the interval between the two rows of support springs 7 and each frequency. As shown in FIG. 13, when the interval between the two rows of support springs 7 (spring interval S) is increased, the drive frequency slightly increases but shows a substantially constant value. On the other hand, the detection frequency is a value less than or equal to the drive frequency when the spring interval S is 20 μm, but as the spring interval S increases, the value increases in a range greater than or equal to the drive frequency value. That is, as the detection frequency changes, the difference from the drive frequency relatively changes. In this case, the spring interval S can be designed freely within a range where the relationship of “drive frequency <detection frequency” is satisfied.

As described above, in order to increase the difference (drive frequency <detection frequency) between the drive frequency (around the Z axis) and the detection frequency (around the X axis), the interval between the two rows of support springs 7 (spring interval S). Need to be larger. However, to increase the distance between the support springs 7 on the anchor 6 side (spring distance S), the anchor 6 itself must be formed large so as to correspond to the spring distance S. When the anchor 6 is increased in size, the slit 8 and the movable weight 4 are also increased in size, and as a result, the rotary vibration gyro 1 cannot be reduced in size. Further, if the slit 8 is opened larger than necessary with respect to the size of the movable weight 4, there is a possibility that the strength of the movable weight 4 is reduced.

Therefore, in the rotational vibration gyroscope 1 according to the present embodiment, the two rows of support springs 7 passed between the anchor 6 and the movable weight 4 are movable compared to the interval (spring interval) on the anchor 6 side. The intervals on the weight 4 side are increased. Thereby, size reduction of the rotational vibration type gyro 1 can be achieved, maintaining the intensity | strength of the movable weight 4 appropriately.

In the second to fifth embodiments, the straight support spring 7 similar to that according to the first embodiment has been described, but instead, “S” similar to that according to the sixth embodiment is used. A letter-shaped support spring 7 may be used.

According to the above configuration, the characteristics of the support springs 7 are adjusted by adjusting the shape and the spring interval S for each row of the pair of support springs 7 spanned between the anchor 6 and the movable weight 4. Any changes can be made. Thereby, the design freedom of the support spring 7 can be improved, and the rotational vibration gyro 1 in which a desired drive frequency and detection frequency are arbitrarily set can be configured.

In addition, this invention is not limited to each embodiment mentioned above at all, In the range which does not deviate from the summary, it can implement with a various form.

1: Rotating vibration type gyro 2: Substrate 3: Drive electrode 4: Movable weight 6: Anchor 7: Support spring 8: Slit 9: Detection electrode 13: Folded part 41: Semicircular movable weight 42: Notch part 44: Movable weight Connection spring 51: outer peripheral end 52: connection 101: drive weight 102: detection weight 114: connection spring

Claims

A movable weight having a slit opening that is released on the substrate and extends in the axial direction of the detection axis through the center of gravity;
A drive electrode for rotating and vibrating the movable weight around the Z-axis passing through its center of gravity;
A detection electrode for detecting a displacement of the movable weight that swings by a Coriolis force around the detection axis;
An anchor that protrudes from the substrate and is concentric with the center of gravity and is inserted into the slit opening to support the movable weight;
Two rows of support springs that are spanned between the anchor and the movable weight, are parallel to the detection axis direction, and are arranged symmetrically about the detection axis. Rotating vibration type gyro.
The support spring is stretched from at least one of both sides of the anchor to at least one of both opening edge portions constituting both ends of the slit opening in the axial direction of the detection shaft. Item 2. The rotational vibration gyroscope according to Item 1.
The rotary vibration gyro according to claim 1, wherein the support spring is formed in a folded shape in an "S" shape.
The rotary vibration gyro according to claim 3, wherein the folded portion folded back in the "S" shape is formed wider than the other portions.
The two rows of support springs are:
4. The rotational vibration gyro according to claim 3, wherein the movable weight side is largely separated and the anchor side is slightly separated.